The described subject matter relates generally to turbine engines, and more specifically to airfoils for turbine engines.
When used on aircraft, gas turbine engines typically include a fan delivering air into a bypass duct and into a compressor section. Air from the compressor is passed downstream into a combustion section where it is mixed with fuel and ignited. Products of this combustion pass downstream over turbine rotors driving them to rotate. Turbine rotors drive the compressor and fan rotors.
Historically, the fan rotor was driven at the same speed as a turbine rotor. More recently, it has been proposed to include various gear reduction schemes to optimize the efficiency of both the fan and the compressor. This generally allows for increased fan diameters and resultant increases in the volume of air delivered into the bypass duct relative to the power core. With this relative increase in what is generally described as the bypass ratio, the relative weight and stresses on fan blades increases accordingly. At higher bypass ratios, the additional airfoil and attachment mass needed to reinforce traditional hollow fan blade constructions against bird strikes and other foreign object damage (FOD) can offset many efficiency gains from higher bypass flows. While certain hollow blade constructions such as certain diffusion bonded arrangements, can achieve weight savings, such blades are difficult to scale up to a high-throughput process without substantial investments.